This application is the national phase under 35 U.S.C. § 371 of PCT International Application No. PCT/JP02/02266, which has an International filing date of Mar. 11, 2002, and which designated the United States of America.
1. Field of the Invention
The present invention relates to a washing machine for washing clothes and other articles of cloth.
2. Description of Related Art
With a washing machine (electric washing machine), washing is typically achieved by putting pieces of laundry in a washing tub and making them flow together with water having detergent dissolved in it (so as to form them into a whirling stream, or agitate them) inside the washing tub. Alternatively, washing is achieved by rotating the washing tub itself. In either way, the articles put in the washing tub are washed all together so that the effect of washing is exerted uniformly on every part of the laundry. However, heavily soiled parts of laundry, for example collars, cuffs, and stained parts, often cannot be cleaned satisfactorily with all-together washing as described above. In such cases, particularly dirty parts of laundry need to be washed separately by hand.
For this reason, attempts have been made to equip a washing machine with a partial washing apparatus for washing parts of laundry. An example is disclosed in Japanese Patent Application Laid-Open No. H2-5996. This publication discloses a washing machine incorporating a partial washing apparatus, which is composed of a rotary washing member, having brush members and protuberances provided around it, and a washing board so that an article of laundry is nipped between the rotary washing member and the washing board and is thereby washed through brushing and rubbing.
Another example of a washing machine equipped with a partial washing apparatus is disclosed in Japanese Patent Application Laid-Open 2000-61192. This publication discloses a washing machine that employs a supersonic washing apparatus as the partial washing apparatus. Now, the structure of a washing machine of the type disclosed in this publication will be described with reference to FIGS. 21 and 22.
The washing machine 1 shown in FIG. 21 is of a full automatic type, and has a main unit 2, which is structured as follows. The main unit 2 has an outer casing 10. The outer casing 10 has the shape of a rectangular parallelepiped, and is formed of metal or synthetic resin. The outer casing 10 is open at the top and bottom. A top plate 11 formed of synthetic resin is laid over the top opening of the outer casing 10, and is fixed to the outer casing 10 with screws. In FIG. 21, the front face and rear face of the main unit 2 are shown on the left and right, respectively, of the drawing. A back panel 12 formed of synthetic resin is laid on the top surface of the top plate 11, in a rear portion thereof, and is fixed to the top plate 11 with screws. A base 13 formed of synthetic resin is laid under the bottom opening of the outer casing 10, and is fixed to the outer casing 10 with screws. In the four corners of the base 13 are formed, integrally therewith, feet 14 for supporting the main unit 2 on a floor. It is to be noted that none of the screws mentioned thus far are shown in the figure.
In the top plate 11 is formed a laundry entrance 15 through which laundry is put in the washing tub as described later. The laundry entrance 15 is fitted with a lid 16 that covers it from above. The lid 16 is divided into a front lid 16a and a rear lid 16b, which are hinged together with a shaft 17 so as to be foldable in two. The rear lid 16b is hinged to the top plate 11 with a shaft 18. The shaft 18 is provided horizontally in front of the back panel 12 so as to extend perpendicularly to the plane of the figure. Thus, the rear lid 16b is rotatable in a vertical plane. The shafts 17 and 18 are parallel to each other. Thus, the front lid 16a also is rotatable in a vertical plane relative to the rear lid 16b. Making the lid 16 foldable in two in this way helps reduce the rotation radius thereof, and thus permits the lid 16 to be opened even when an obstacle is placed above the washing machine 1 close thereto.
Inside the outer casing 10, a water tub 20 and a washing tub 30 are arranged. The water tub 20 and the washing tub 30 both have the shape of a cylindrical cup, open at the top. The water tub 20 and the washing tub 30 are arranged concentrically with their axes vertical and with the water tub 20 outside and the washing tub 30 inside. The water tub 20 is suspended by a suspension mechanism 21. The suspension mechanism 21 is composed of suspension members arranged in four positions around the water tub 20 so as to link a bottom portion thereof to each inner corner of the outer casing 10, and supports the water tub 20 in such a way that it is swingable in a horizontal plane.
The washing tub 30 has a peripheral wall that is gently tapered so as to be increasingly wide open upward. Except for a plurality of water discharge openings 31 formed in a circular arrangement in its topmost portion, the peripheral wall has no opening that permits liquid through. Around the rim of the top opening of the washing tub 30, a ring-shaped balancer 32 is fitted. The balancer 32 serves to reduce vibration when the washing tub 30 is rotated at high speed when laundry is dewatered. On the inner bottom surface of the washing tub 30, a pulsator 33 is arranged. The pulsator 33 serves to produce a flow of washing fluid or rinsing water inside the washing tub 30.
On the outer bottom surface of the water tub 20, a drive unit 40 is mounted. The drive unit 40 includes a motor 41, a clutch mechanism 42, and a brake mechanism 43. From the center of the drive unit 40, a washing tub shaft 44 and a pulsator shaft 45 protrude upward. The washing tub shaft 44 and the pulsator shaft 45 form a double shaft, with the washing tub shaft 44 outside and the pulsator shaft 45 inside. The washing tub shaft 44 penetrates the water tub 20, and couples to the washing tub 30, thereby supporting it. The pulsator shaft 45 penetrates the washing tub 30 as well, and couples to the pulsator 33, thereby supporting it. The gap between the washing tub shaft 44 and the water tub 20 and the gap between the pulsator shaft 45 and the washing tub 30 are sealed with sealing members to prevent leakage of water.
In the space between the top plate 11 and the back panel 12 is arranged a water feed valve 50 that is opened and closed electromagnetically. The water feed valve 50 has a connection pipe 51 that penetrates the back panel 12 and protrudes upward. The connection pipe 51 connects to a water feed hose (not shown) through which clean water, such as tap water, is supplied. From the water feed valve 50, a water feed nozzle 52 extends frontward. The tip of the water feed nozzle 52 reaches above the washing tub 30. Though not shown, a mixing device for mixing detergent, fabric softener, or the like with water is provided in the water passage from the water feed valve 50 to the tip of the water feed nozzle 52. To the bottom of the water tub 20, an air trap 53 is coupled. From the air trap 53, a connecting pipe 54 extends upward. To the top end of the connecting pipe 54, a water level switch 55 is connected.
To permit the water in the water tub 20 and in the washing tub 30 to be drained out of the main unit 2, a drain hose 60 is provided. The drain hose 60 is connected, immediately below the water tub 20, to branch pipes 60a and 60b, of which one 60a connects to the bottom of the water tub 20 in a portion near the periphery thereof and the other 60b connects thereto in a portion near the center thereof. To the inner bottom surface of the water tub 20, a ring-shaped partition wall 61 is fixed so as to enclose the portion of the water tub 20 where the branch pipe 60b is connected. On top of the partition wall 61, a ring-shaped sealing member 62 is fitted. The sealing member 62 is kept in contact with the outer peripheral surface of a disk 63 fixed to the outer bottom surface of the washing tub 30, forming a separate drain space 64 between the water tub 20 and the washing tub 30. The drain space 64 communicates with the inside of the washing tub 30 through a drain outlet 65 formed in the bottom of the washing tub 30. The air trap 53 connects to the drain space 64. The branch pipe 60b is provided with a drain valve 66 that is opened and closed electromagnetically.
In a front portion of the main unit 2, a partial washing apparatus 70 is provided. The partial washing apparatus 70 is provided with an arm 72 that rotates in a horizontal plane about a vertical shaft 71 provided on the bottom surface of the top plate 11. To the tip of the arm 72, a supersonic washer 73 is fitted. The supersonic washer 73 has a supersonic vibration horn. When not in use, the partial washing apparatus 70 is retracted to beneath the top plate 11, as indicated by broken lines in FIG. 22. When in use, the partial washing apparatus 70 is pulled out, as indicated by solid lines, so that the supersonic washer 73 is located around the center of the laundry entrance 15. Inside the arm 72 are laid a water feed tube and electric leads for feeding cleaning fluid and electric power, respectively, to the supersonic washer 73. The supersonic washer 73 has a gap 74 formed therein to permit an article of laundry to be passed therethrough. The washing machine is intended for use in a household, and therefore the supersonic washer 73 is designed to offer a high degree of safety.
Under the top plate 11, a controller 80 is arranged. The controller 80 feeds commands to the drive unit 40, the water feed valve 50, and the drain valve 66. The controller 80 also feeds display commands to a display (not shown) provided on the top surface of the top plate 11. The controller 80 includes a circuit for controlling the supersonic washer 73.
The washing machine 1 described above operates as follows. With the partial washing apparatus 70 retracted beneath the top plate 11, articles of laundry are put in the washing tub 30 through the laundry entrance 15, and the lid 16 is closed. Through operation of operation buttons (not shown) arranged on the top surface of the main unit 2, the desired course of washing is selected, and the starting of operation is commanded. Thus, the washing machine 1 starts operating automatically. First, the amount of laundry is determined. Then, water is supplied to the washing tub 30 through the water feed nozzle 52. Here, the drain valve 66 is closed. The water level switch 55 monitors the level of water in the washing tub 30. When the water level switch 55 detects that an amount of water commensurate with the amount of laundry has pooled in the washing tub 30, the water feed valve 50 is closed. Here, the water is mixed with detergent before it is discharged out of the water feed nozzle 52, and thus the water pooled in the washing tub 30 is washing fluid having the detergent dissolved in it.
Next, a washing process is started. In the washing process, the motor 41 rotates the pulsator 33. As the pulsator 33 rotates, the washing fluid flows, washing the laundry. Here, the brake mechanism 43 applies a brake to the washing tub shaft 44. Thus, the washing tub 30 does not rotate together with the washing fluid and the laundry. A predetermined period thereafter, the motor 41 stops, and thus the pulsator 33 stops rotating. In addition, the drain valve 66 opens. The washing fluid in the washing tub 30 is drained through the drain space 64. When, a predetermined period thereafter, the most of the washing fluid has drained out of the laundry, the clutch mechanism 42 is switched so that now the motor 41 rotates the washing tub shaft 44. This causes the washing tub 30 to rotate at high speed for dewatering. Here, the pulsator 33 rotates together with the washing tub 30.
As the washing tub 30 rotates at high speed, the laundry is pressed against the inner peripheral wall of the washing tub 30 by centrifugal force. The washing fluid contained in the laundry also gathers on the inner surface of the peripheral wall. Since the washing tub 30 is tapered so as to be increasingly wide open upward as described earlier, the washing fluid acted on by the centrifugal force rises along the inner surface of the washing tub 30. When the washing fluid reaches the top end of the washing tub 30, it is discharged through the discharge openings 31. After being discharged through the discharge openings 31, the washing fluid hits the inner surface of the water tub 20, and flows down, along the inner surface of the water tub 20, to a bottom portion of the water tub 20. The washing fluid is then drained out of the main unit 2 through the branch pipe 60a and then the drain hose 60.
After the laundry is dewatered sufficiently, the drain valve 66 is closed. Then, water for rinsing is supplied through the water feed nozzle 52. When a predetermined amount of rinsing water has pooled in the washing tub 30, the pulsator 33 is rotated to agitate the rinsing water and the laundry. This causes the dirt and detergent components left in the laundry to be released into the rinsing water. A predetermined period thereafter, the pulsator 33 is stopped. Then, the drain valve 66 is opened to discharge the rinsing water. Then, the washing tub 30 is rotated for dewatering so that water is shaken out of the laundry. Rinsing and dewatering processes like these are repeated a predetermined number of times. When the last dewatering process is complete, a whole washing procedure is complete.
In the above descriptions, it is assumed that rinsing is achieved by “pooled-water rinsing,” i.e. rinsing performed with rinsing water pooled in the washing tub 30. However, it is also possible to achieve rinsing by “shower rinsing,” i.e. rinsing performed while the washing tub 30 is rotated at low speed with water kept supplied through the water feed nozzle 52. Whether to adopt pooled-water rinsing, shower rinsing, or both is determined according to the selected course of washing and the amount of laundry.
In cases where dirt persists after washing, or where there are stubborn stains that are unlikely to be removed through an ordinary course of washing, the partial washing apparatus 70 is used to wash particularly dirty parts of laundry. Specifically, the partial washing apparatus 70 is pulled out from the non-use position indicated by the broken lines in FIG. 22 to the use position indicated by the solid lines. With the partial washing apparatus 70 in this position, the supersonic washer 73 is driven while the cleaning fluid is supplied. In this state, a dirty part of laundry is passed through the gap 74, so that this part is cleaned by the synergistic effect of supersonic waves and cleaning fluid.
After sufficient partial washing is performed, the laundry is put in the washing tub 30. Then, if a washing process had been finished before the partial washing, rinsing and dewatering processes are performed, or, if a washing process has not been finished yet, a washing procedure is started with a washing process.
The washing machines disclosed in Japanese Patent Application Laid-Open No. H2-5996 and Japanese Patent Application Laid-Open 2000-61192 mentioned above both incorporate a partial washing apparatus inside the main body of the washing machine. This poses the following problems. First, the partial washing apparatus is located in a position lower than the top face of the washing machine (specifically about 750 to 800 mm above the floor surface). This forces the user, when using the partial washing apparatus, into a slightly stooped posture, depending on his or her height. This puts a heavy burden on the user's body, producing severe fatigue. This can be solved by bringing the partial washing apparatus to a higher position. However, this increases the height of the main body of the washing machine, bringing the laundry entrance to a higher position, and thus makes it difficult to put in and take out laundry. Second, the brush and the supersonic vibration horn for achieving partial washing are not guarded. This poses a risk of the user's hand touching those components. If the user's hand touches the brush, it is scarred, and may even be pinched between the brush and the washing board. If the user's hand touches the supersonic vibration horn, it aches, and its cartilaginous tissue may be affected adversely by the vibration, which is in such a frequency range as to reach deep into the human body.